Fuel injection device for internal combustion engines

ABSTRACT

An improved device for controlling, either directly or indirectly, the injection of pressurized fuel into an internal combustion engine. The device comprises a body having a fuel inlet, a fuel outlet and a fuel return, as well as a valve mounted therein. The valve is actuated by an electromagnet and is adapted to establish communication between the fuel inlet and the fuel outlet when the valve is actuated. The device has a fuel accumulator comprising an opening in one side of the body and a diaphragm mounted across the opening to form an enclosed volume within the body. The enclosed volume communicates with the fuel input so that the diaphragm deflects outwardly with respect to the interior of the body in response to increases in the pressure of the pressurized fuel provided to the fuel input. The improvement comprises a pressure regulator having a regulatory valve disposed within the body and actuated by the diaphragm. The regulatory valve has an input in communication with the enclosed volume and an output in communication with the fuel return. The regulatory valve is adapted to establish communication between the enclosed volume and the fuel return when the pressure of the pressurized fuel in the enclosed volume reaches a predetermined value.

United States Patent 91 Sallot FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINES [75] Inventor: Georges Sallot,

France Elisabethville,

[73] Assignee: Societe Des Procedes Modernes DInjection Sopromi, Les Mureaux, France [22] Filed: Dec. 17, 1971 [21] App]. No.: 209,227

[52] [1.8. CI. ..l23/136, 123/32 AE, 137/613,

4 123/32 EA [51] Int. Cl ..F02m 39/00 [58] Field of Search 123/136, 32 EA, 32 AE,

[56] References Cited UNITED STATES PATENTS Primary Examiner--Laurence M. Goodridge Assistant Examiner-Cort R. Flint Attorney.lohn Q. McQuillan et al.

[451 May 1, r973 5 7] ABSTRACT An improved device for controlling, either directly or indirectly, the injection of pressurized fuel into an internal combustion engine. The device comprises a body having a fuel inlet, a fuel outlet and a fuel return, as well as a valve mounted therein. The valve is actuated by an electromagnet and is adapted to establish communication between the fuel inlet and the fuel outlet when the valve is actuated. The device has a fuel accumulator comprising an opening in one side of the body and a diaphragm mounted across the opening to form an enclosed volume within the body. The enclosed volume communicates with the fuel input so that the diaphragm deflects outwardly with respect to the interior of the body in response to increases in the pressure of the pressurized fuel provided to the fuel input. The improvement comprises a pressure regulator having a regulatory valve disposed within the body and actuated by the diaphragm. The regulatory valve has an input in communication with the enclosed volume and an output in communication with the fuel return. The regulatory valve is adapted to establish communication between the enclosed volume and the fuel return when the pressure of the pressurized fuel in the enclosed volume reaches a predetermined value.

7 Claims, 2 Drawing Figures Patented May 1, 1973 2 Sheets-Sheet 1 Patented May 1, 1973 3,730,159

2 Sheets-Sheet 2 FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The present invention concerns improvements to a device for directly or indirectly controlling the fuel for an internal combustion engine.

.One such device is described in US. Pat. application Ser. No. 135,963 for Control System for the Injection of Fuel Into Internal Combustion Engines", filed Apr. 21, 1971. The description of the device contained therein is incorporated by reference in this specification as though fully rewritten herein.

Briefly, the device comprises an electromagnetic metering valve which receives an electric signal having a duration which varies as a function of the operating conditions of the engine. The valve is disposed between a source of fuel under pressure and valve-type or needle-type mechanical injectors in a fashion that is of itself known. The metering valve has three flow paths. One of the paths is connected to the source of fuel under pressure while the second path is connected to the mechanical injectors either directly or through the intermediary of a sequential distributor. The third path is'connected to a fuel-return conduit kept at a pressure lower than the calibrated pressure of the injectors. The metering valve is moreover arranged in such a way that, at the beginning or at the end of the electric signal, a connection is established between these three paths.

In accordance with another characteristic of the device, the metering valve comprises an annular hollow sliding piston having two positions. The piston is guided in sealed fashion in the body of the valve and is provided with a first face that in one position of the piston cooperates with a conical seat in the body. The inlet for the fuel under pressure is situated in an annular space between the conical seat and the guiding of the piston in the body, while the outlet to the injectors runs from a bore in the axis of the conical seat. The piston, which is integral with the mobile armature of the control electromagnet, comprises a second face that in another position of the piston cooperates with a second conical seat. The interior of the piston is in communication with the outlet to the injectors, while the annular space between the second conical seat and the body of the metering valve is connected to the return-flow conduit. Finally, in the device there is a provision for making the support for the valve body in the form of a flange having a central opening in communication with the fuel under pressure. The opening is closed by a diaphragm being held in position by the edge of a cover screwed on the flange. A spring is disposed between the diaphragm and the cover in such a way that the space defined by the opening and the diaphragm constitutes a hydraulic'pressure accumulator.

These arrangements. and others that are described in the co-pending application provide an injection control device of very small bulk and of reliable and precise operation. However, the injection control device still necessitate the provision of a separate pressure regulator, and also the provision of a means disposed in the fuel-return conduit going to the tank for maintaining a certain back-pressure in this return flow conduit, for example, a means comprising a calibrated valve. Thus, the complete installation is relatively expensive to make, and it does not always provide the reliable functioning that should be achieved.

SUMMARY OF THE INVENTION The present invention has the purpose of avoiding these deficiencies, and it has for its object improvements to the injection control device which controls the injection of fuel into internal combustion engines directly or indirectly. The invention is characterized by the fact that the diaphragm is connected to the regulatory valve of a pressure regulator disposed in the base of the body. When the pressure of the fuel reaches a certain value, the regulatory valve establishes communication between the opening, and thus the fuel input, and the fuel return, thereby providing a pressure regulated by-pass for the pressurized fuel.

In accordance with the present invention, the regulatory valve of the pressure regulator comprises a piston which slides in sealed fashion in an appropriate bore in the body of the device. At a certain distance from the end thereof, which is integral with the diaphragm, the piston has transverse parts. These parts cooperate with the bore within which the piston slides to place the hollow interior of the piston in communication with the opening in the base of the body through the transverse parts when the diaphragm is displaced a predetermined amount. The displacement of the diaphragm is a function of the fuel pressure. The interior of the piston is also placed in communication with the fuel-return conduit.

Further, a valve is provided in the fuel-return conduit at the outlet from the body of the device. The valve is calibrated at a certain pressure in such a way as to maintain, in the interior of the body of the device upstream of the said valve, a predetermined counter-pressure.

BRIEF DESCRIPTION OF THE FIGURES By way of an example and to facilitate understanding of the following description of one embodiment of the invention, reference is made to the accompanying drawings wherein:

FIG. 1 is a schematic representation of one injection system in accordance with the invention.

FIG. 2 is a schematic section of a device for controlling the injection of fuel in accordance with the invention.

DESCRIPTION OF ONE EMBODIMENT Referring to FIG. 1, the engine includes an intake manifold 51 associated with the individual pipes opening into the different engine cylinders through conventional mechanical injectors, return flap valves or needle valves. The fuel is delivered out of thecontainer 46 by the pump 50 and delivered into the electromagnetic measuring valve 3 through the filter 49. The excess fuel returns into the container 46 under control of a pressure regulator 48. A pressure accumulator 47 which may, if required, form a unit with the measuring valve 3 is also provided. The measuring valve 3 is connected with an input conduit 3a and with a liquid output conduit 312 wherein the liquid is subjected to a modulated pressure leading to the injectors 4 either directly or else through a sequential distributor 9.

A pulse transmitter 2 controlled by the rotation of the engine is adapted to actuate the electronic system 5 producing the signal controlling the measuring valve 3 and to actuate the distributor 9 to define sequentially the operation of the injectors. The electronic system 5 produces, as well-known in the art, an electric signal under control of the operative conditions of the engine. The signal controls the amount of fuel to be injected by adjusting the duration of opening periods of the conduits 3a and 3b controlled by the measuring valve 3. Obviously, the injectors may be designed in a manner such that they provide direct injection into the combustion chamber of the engine instead of resorting to indirect injection as in the case illustrated, this modification remaining within the scope of the invention. Electric energy is fed to the electronic system 5 by the supply 53 under control of the switch 52. The device 65 includes parts 3 and 47-49.

Referring to FIG. 2 it is seen that the metering valve 3 of the device 65 of the present invention is combined with a hydraulic accumulator 47 integral with it. The body 6 of the metering valve 3 comprises the connection for the conduit 3a supplying the liquid fuel under pressure, and having its outlet, connected through the intermediary of the filter 49, mounted in the filter body 61 and fastened in it by the nut 60, into an opening 6fin the support of the said body. The connections for the outlet conduit 3b of the liquid fuel runs to injectors 4, and the return flow connection 3c for the liquid fuel runs to the tank 46.

The upper element 7 comprises the electromagnet which controls the movement of the annular piston 10. The electromagnet is of annular form with a fixed armature 12 having an inverted U-cross-section. The winding 13 of the electromagnet is housed in the interior of the U-shaped armature 12 and is connected to a terminal 14 fastened in the upper element 7 through the intermediary of an insulating ring 15. The wire 13b of the winding 13 is soldered to the element 7 for grounding. It should be noted that with this arrangement the Foucault or eddy currents that might be produced in the fixed armature 12 are not able to assume a circular path because they are cut by one or more radial slots (not shown) made in the fixed armature 12. However, in order to avoid eddy currents in the fixed armature 12, it is in addition carefully insulated from the upper element 7 of amagnetic material by a sheet 30 of insulating material and by the slot 7b filled with fuel. After the electromagnet has been put in place in the upper element 7, the surface of armature 12 facing the body 6 is substantially coplanar with the surface of upper element 7 facing the body 6.

The electromagnet l2 and 13 activates the annular piston 10. To accomplish this effect, the mobile armature 21 is made integral with the piston by the forming of the edge 21a over a corresponding shoulder of the piston. The annular piston slides in a sealed manner between two positions in the body 6. This scaling is secured by a matched assembly with very slight radial clearance. The travel of piston 10 between its two positions is limited by the conical sealing surfaces 6a and 11b in the body 6 and the guide element 11, respectively. However, the maximum air-gap corresponding to contact of the sealing edge 10b with the conical surface 6a is regulated by a shim or spacer 28 disposed between the upper element 7 and the body 6. The minimum airgap or residual air-gap, corresponding to contact of the sealing edge 100 with the conical surface 11b, is regulated by another shim or spacer 29 disposed between the upper element 7 and the guiding element 11'. For this purpose the upper face of the body 6, as well as that of the mobile armature 21 and the cylindrical element 11, are also trued up so as to be disposed in a common plane with all the elements being assembled in their places. By this simple means of machining and assembling there are avoided the difficulties of manufacturing tolerances in making the elements. By way of example only, it may be noted that the maximum air-gap is of the order of 0.1 5 mm, while the residual air-gap is of the order of 0.05 mm. The travel of the annular piston 10 is therefore about 0.10 mm.

As can be seen, the cylindrical element 11 is installed slidingly in the annular piston 10 and bears against that piston through the intermediary of a return motion spring 19 which bears by one of its ends in the annular piston 10 and by its other end against a shoulder 20b of the regulating screw 20.

After the assembly of the metering valve 3 and after removing the plug 37, the tension of the return motion spring 19 can be regulated by a screwdriver inserted into the slot 200 of the regulating screw 20.

In the position of the annular piston 10 that is shown, i.e., the electromagnet not being energized, the outlet connection 3b is in communication with the returned liquid conduit 30. This is accomplished by way of the central bore 6e, the interior of the annular piston 10, the cylindrical guiding element 11, the annular space 6c and the annular space 6i, in such a manner that the injectors 4 are subjected to a low pressure that is equal to a pressure of the order of 2 to 3 bars, in order to avoid a formation of vapor bubbles in the circuit at high operating temperatures. Nevertheless the counter-pressure must be less than the calibrated pressure of the injectors.

The aforesaid counter-pressure is obtained by means of a check valve mounted in the outlet conduit 3c and comprises a valve body 43 and a ball 44 pressed against its seat by the coil spring 45. A toroidal seal 46 is provided to insure a leakproof seal.

When the electromagnet l2 and 13 is excited,'its mobile armature 21 is attracted upward and the sealing edge 10a of the annular piston 10 comes into contact with the conical surface 11b. This terminates communication of the central bore 6e with the connector 3c, while establishing communication of the pressured liquid supplying connector 3a to the outlet connector 3b for the injectors. This is accomplished through the opening 6fin the base of the body 6, the passage 6d, the annular space 6b, the passage between the sealing edge 10b and the conical surface 6a, and the central bore 6e. The outlet connector is communicatively connected to the central bore 6e.

The pressure accumulator 47 comprises a diaphragm 23 clamped by the cover 8 against the body 6. The diaphragm 23 is guided by the piston 24 and the dome 36, which are clamped against one another by the screw 26, which is integral with the piston 35 and the nut 26a. The diaphragm 23 is pressed against by the spring 25, which bears on the one hand against the interior of the piston 24, and on the other hand against the abutment 31. The position of the abutment 31 can be regulated by the regulating screw 32, which is locked in position by the nut 40 through the intermediary of the washer 33.

transverse parts 35b which place the hollow interior 35a of the piston into communication with the opening 6f when the parts 351: pass beyond the edge 61 of the cylindrical casing 6m for the piston 35. in this position communication is established between the opening 6f, the annular space 6k at the base of the cylindrical casing 6m, the passages 6g and 612, the annular space 6i and the outlet connector 3c. The passage 6g is moreover closed off from the outside by a press-fit ball 34.

It may therefore be considered that the construction of the regulatory valve of the pressure regulator in the form of a piston permits combining the function of a pressure accumulator 4'7 with the function of a pres sure regulator 48. in fact, as long as the transverse ports 35b do not reach the edge 61 of the cylindrical casing 6m, the pressure in the opening dfis solely a function of the force exerted by the spring 25, which varies linearly with the displacement of the piston 35, on the diaphragm 23 which is integral with it through the intermediary of the piston 24 and the dome 36.

The characteristic of the spring 25 is of course chosen so that the force varies linearly with a very small slope so that the variation of the pressure between the position of rest, as illustrated in FIG. 2;, and the position in which the transverse ports 35b are uncovered may be as small as possible. When the transverse ports 35b are uncovered, the piston 35 operates like the valve of a pressure regulator; that is to say, the displacements of the piston as a function of the supply that should pass through it are of very small amplitude because the passageway section of the ports 3519 increases very rapidly with the displacement of the piston 35. Therefore, the pressure remains practically constant from the time when the transverse ports 35b reach the edge til of the cylindrical casing 6m. The three elements 7, 6 and 8, are clamped together by gudgeons 27, which are on the one hand screwed directly into a threaded hole in the element 7, and are on the other hand tightened up by a nut 39 through the intermediary of a washer 38. Centering of the element 7 relativelyto the body 6 is obtained by a cylindrical ring 42. Sealing between the body and the upper element 7 is secured by the toroidal seals 41.

It should be noted that the arrangement according to the invention not only permits a compact construction of small bulk, but also the functioning of the device is improved because of the fact that the pressure regulator is disposed in the interior of the injection control device. This latter improvement permits a constant flow of the fuel through the device to be obtained, thus ensuring cooling of the entire device and the avoidance of the possibility of the formation of vapor bubbles therein.

i What is claimed is:

1. An improved device for controlling the injection of pressurized fuel from a source of fuel on an internal combustion engine, the device having a body having a fuel input adapted to receive the pressurized fuel, a fuel output adapted to provide fuel to injectors, and a fuel return adapted to'return fuel to the fuel source, a valve mounted within the body, the valve having a first path therein communicatively connected to the fuel input, a

second path therein connected to the fuel output and a third path therein connected to the fuel return, an electromagnet mounted within the body for actuating the valve, the valve being adapted to place the fuel input into communication with the fuel output when it is actuated, the body having an opening in one surface thereof, a diaphragm mounted across the opening in the body to form an enclosed volume within the body, the enclosed volume being communicatively connected to the fuel input, the diaphragm being adapted to deflect outwardly away from the enclosed volume in response to increases in the pressure of the fuel to be provided to the fuel input, the improvement comprising a pressure regulator disposed within the body and having a regulatory valve, the regulatory valve having an input in communication with the enclosed volume and an output in communication with the fuel return, the regulatory valve being adapted to establish communication between the enclosed volume and the fuel return when the pressure of the pressurized fuel to be provided to the fuel input reaches a predetermined value.

2. A device in accordance with claim 1 and further defined wherein the regulatory valve of the pressure regulator is adapted to establish the communication between the enclosed volume and the fuel return in" response to a predetermined deflection of the diaphragm caused by a predetermined pressure of the pressurized fuel to be provided to the fuel input.

3. A device in accordance with claim 2 and further defined wherein the regulatory valve of the pressure regulator comprises a bore in the body of the device and a piston mounted in the bore for movement in a first and a second direction, the piston having a hollow interior and having transverse ports disposed at a predetermined distance from one end of the piston, the transverse ports extending from the exterior of the piston to the hollow interior thereof, the hollow interior of the piston being in communication with the bore adjacent the other end of the piston, the bore being in communication with the fuel return, the piston being adapted for movement in the first direction in response to an outward deflection of the diaphragm and for movement in the second direction in response to an inward deflection of thediaphragm, the piston and the bore being adapted to place the enclosed volume, and thus the fuel input, in communication with the fuel return through the transverse ports and the hollow interior of the piston when the piston moves at least a predetermined distance in the first direction in response to a predetermined deflection of the diaphragm.

4. A device in accordance with claim 3 and further defined wherein the one end of the: piston is coupled to the diaphragm for movement therewith.

5. A device in accordance with claim 2 and further defined wherein the diaphragm deflects outwardly in pressurized fuel to be provided to the fuel input passes circulates about the valve.

7. A device in accordance with claim 2 and further comprising a valve in the fuel return of the body of the device, the valve being adapted to remain closed until the hydraulic pressure of the pressurized fuel to be provided in the interior of the body reaches a predetermined pressure upstream of the valve, thus establishing a predetermined counter pressure for the fuel within the device 

1. An improved device for controlling the injection of pressurized fuel from a source of fuel on an internal combustion engine, the device having a body having a fuel input adapted to receive the pressurized fuel, a fuel output adapted to provide fuel to injectors, and a fuel return adapted to return fuel to the fuel source, a valve mounted within the body, the valve having a first path therein communicatively connected to the fuel input, a second path therein connected to the fuel output and a third path therein connected to the fuel return, an electromagnet mounted within the body for actuating the valve, the valve being adapted to place the fuel input into communication with the fuel output when it is actuated, the body having an opening in one surface thereof, a diaphragm mounted across the opening in the body to form an enclosed volume within the body, the enclosed volume being communicatively connected to the fuel input, the diaphragm being adapted to deflect outwardly away from the enclosed volume in response to increases in the pressure of the fuel to be provided to the fuel input, the improvement comprising a pressure regulator disposed within the body and having a regulatory valve, the regulatory valve having an input in communication with the enclosed volume and an output in communication with the fuel return, the reGulatory valve being adapted to establish communication between the enclosed volume and the fuel return when the pressure of the pressurized fuel to be provided to the fuel input reaches a predetermined value.
 2. A device in accordance with claim 1 and further defined wherein the regulatory valve of the pressure regulator is adapted to establish the communication between the enclosed volume and the fuel return in response to a predetermined deflection of the diaphragm caused by a predetermined pressure of the pressurized fuel to be provided to the fuel input.
 3. A device in accordance with claim 2 and further defined wherein the regulatory valve of the pressure regulator comprises a bore in the body of the device and a piston mounted in the bore for movement in a first and a second direction, the piston having a hollow interior and having transverse ports disposed at a predetermined distance from one end of the piston, the transverse ports extending from the exterior of the piston to the hollow interior thereof, the hollow interior of the piston being in communication with the bore adjacent the other end of the piston, the bore being in communication with the fuel return, the piston being adapted for movement in the first direction in response to an outward deflection of the diaphragm and for movement in the second direction in response to an inward deflection of the diaphragm, the piston and the bore being adapted to place the enclosed volume, and thus the fuel input, in communication with the fuel return through the transverse ports and the hollow interior of the piston when the piston moves at least a predetermined distance in the first direction in response to a predetermined deflection of the diaphragm.
 4. A device in accordance with claim 3 and further defined wherein the one end of the piston is coupled to the diaphragm for movement therewith.
 5. A device in accordance with claim 2 and further defined wherein the diaphragm deflects outwardly in two stages, the first stage of outward deflections encompasses from zero deflection to the predetermined deflection and the second stage of deflections encompasses further outward deflections of the diaphragm, during the first stage of deflections the enclosed volume being adapted to function as an accumulator for the pressurized fuel to be provided, further outward deflection of the diaphragm causing the regulatory valve of the pressure regulator to open whereby the pressurized fuel to be provided to the fuel input passes from the enclosed volume to the fuel return.
 6. A device in accordance with claim 2 and further defined wherein a passage is formed in the body of the device adjacent to and about the valve, the passage being in communication with the fuel return, the second path of the valve and the output of the regulatory valve, whereby pressurized fuel passing from the enclosed volume through the regulatory valve to the fuel return in response to the opening of the regulator valve circulates about the valve.
 7. A device in accordance with claim 2 and further comprising a valve in the fuel return of the body of the device, the valve being adapted to remain closed until the hydraulic pressure of the pressurized fuel to be provided in the interior of the body reaches a predetermined pressure upstream of the valve, thus establishing a predetermined counter-pressure for the fuel within the device. 